Treatment of clays



United States ate 2,761,842 TREATMENT OF CLAYS William E. Brown,Gibsonia, and Clifford R. Giacobine,

Oakmont, Pa., assignors to Gulf Research & Development Company,Pittsburgh, Pa., a corporation of Delaware No Drawing. ApplicationNovember 18, 1954, Serial No. 469,861

Claims. (Cl. 252-855) This invention relates to a process of treatingbodies comprised wholly or in part of clays, including clay-likematerials, for the purpose of maintaining and/or restoring thepermeability to fluids of such bodies and renderor all of thepermeability they may possess when they are subjected to the action ofliquids such as water, certain brines, emulsions containing water orcertain brines, etc. Treatment of such clay bodies in accordance withthe process of this invention will render them permeable, prevent areduction in fluid permeability and/or restore fluid permeability tothose clay bodies in which it has been lost. As a result of thetreatment the resistance of the clay bodies to mechanical and/orchemical disintegration will also be substantially increased.

The clay or clay-like materials which can be treated in accordance withour invention can include any natural geologic formations or artificialformations such as rail- I W t a road or highway embankments, road bedsand road surfaces, automobile parking areas, areas for outdoor sports,storage areas, military installations, etc. Included also among thematerials which can be treated to improve or maintain their permeabilityand their physical and/or chemical stability are manufactured articlescontaining 1 clays or clay-like materials. As an example, but withoutbeing limited thereto, this process can be employed to treat articlescast, extruded or otherwise formed from clay to increase theirmechanical strength prior to and/or after firing.

The process of this invention has particular applicability in thetreatment of natural geologic formations for the purpose of preventingor correcting the loss in permeability thereof caused by swelling and/ordispersing of the clay contained therein, preserving the approximategeometry of the grains of the formation, maintaining the poredistribution of the formation and firming the formation if it isnncemented or poorly cemented. More specifically, this invention isespecially advantageous in the treatment of a clay-containing formationadjacent a borehole in wells in order to increase, maintain and/ orrestore the permeability of the formation by rendering the claycontained therein resistant to swelling, disruption and/ or migration,and also to shrink essentially irreversibly the hydrated, swollen claywhich may be present in said formations adjacent wells producing fluids,such as hydrocarbons, water, etc., or in wells which are used to injectsuch fluids into a geologic formation. The clay in the formation can bethat which was present originally, or it can be clay which wasintroduced into the formation in the process of creating the borehole,e. 'g., by the use of a clay-containing drilling mud, or insubsequentoperations. w

The clay originally present in the formation can. reduce thepermeability of the formationby swelling and/ or migrating to formbridges or blocks in the pores of the formation or in perforations incasing, screens, etc., used in well completions, as a result of contactof said clay with aqueous liquids such as water, certain brines,emulsions containing Water or certain brines, etc. This liquid can beintroduced into the formation as drilling mud filtrate, injection water,water from leaks in or behind the casing, or ground water associatedwith the formation. Of particular concern in the case of introduced clayis that clay which, as a component of the drilling mud, invades theformation during the drilling of the borehole. High swellingmontmorillonite is often used in drilling muds, among other reasons,because of its ability to create a low permeability filter cake on theformation. Under some conditions, a low permeability Zone is createdwithin the formation in the vicinity of the borehole from invasion bythe drilling mud. In addition, if the mud filter cake is not removedcompletely when drilling has been completed, it forms a barrier to theflow of fluid into'or out from the formation. The invention disclosedand claimed herein will shrink the hydrated, swollen clay in theformation, mud cake, and/ or invaded zone so as to substantiallyincrease the permeability and mechanical and chemical stability of theformation.

Among the clays which may be present originally in natural geologicalformations or may have been introduced therein and which can beeffectively treated in accordance with the present invention there areincluded clay minerals of the montmorillonite group such asmontmorillonite, saponite, nontronite, hectorite, and sauconite; thekaolin group such as kaolinite, nacrite, dickite, and halloysite; thehydrous-mica group such as hydrobiotite, glauconite, illite andbramallite; the chlorite group such as chlorite and chamosite; clayminerals not belonging to the above groups such as vermiculite,attapulgite, and sepiolite; and mixed-layer varieties of the aboveminerals and groups. The clay content of the formations can be comprisedsubstantially of a single species of clay mineral, or of severalspecies, including the mixed-layer types of clay. Of the clay mineralscommonly encountered in the drilling of wells in natural geologicalformations which can be productive of the difliculties herein noted andwhich can be treated effectively in accordance with the presentinvention are clay minerals selected from the class consisting of themontmorilionite group, hydrousmica group, chlorite group, and kaolingroup. It will be understood that the clay formations treated inaccordance with the invention need not be composed entirely of clay butmay contain other mineral components associated therewith.

Clays can swell and/or disperse, disintegrate or otherwise becomedisrupted in the presence of aqueous fluids. A clay which swells is notlimited to expanding latticetype clays but includes all those clayswhich can increase in bulk volume with or without dispersing,disintegrating or otherwise becoming disrupted when subjected to contactwith aqueous solutions such as water, certain brines, etc. Certain clayscan also disperse, disintegrate or otherwise become disrupted withoutswelling in the presence of aqueous solutions such as Water, certainbrines, emulsions containing water or certain brines, etc. Some clays inthe presence of such aqueous solutions will expand and be disrupted tothe extent that they will become unconsolidated and move into aborehole. Formations which consist largely of clay can develop pressureson the order of several thousand pounds per square inch upon absorbingwater in a confined space. The clay materials defined above occur asminute,

equivalent quantity of a granular material such as sand,

This combination of small size and great surface area .results in a highsurface energy with attendant unusual 'surface properties and extremeafiinity for surface-active agents. The structure of some of theseclays, as for instance montmorillonite, can be pictured as a stack ofsheet-like three-layer lattice units which are weakly bonded to eachother and which are expanded in the c crystallographic direction bywater or other substances which can penetrate between the sheets andseparate them.

All clay minerals have ionsexchange properties. Thus, for example,montmorillonite has a cation-exchange capacity of from about 90 to 130milliequivalents. per 1G0 grams of pure clay, illite from about 20 to 40milli equivalents, and kaolinite from about 5 to milliequivalents. Underordinary oil-well conditions the ion-exchange reactions between theclays and substances associated with the clays and capable of reactingtherewith are essentially reversible.

The properties of the clays vary widely with the cations occupying thebase-exchange positions or sites. A baseexchange position or site can bedefined as an area, in this instance on a clay crystal, which hasassociated with it an exchangeable cation. Among the cations which aregenerally found on the base-exchange position or site can be mentionedsodium, potassium, calcium, magnesium, iron, hydrogen, etc. Thesecations are believed to beheld to the clay surface by ionic forces.

The cations occupying the base-exchange sites on the clay can be thoseoriginally present or cations finding their way to the base-exchangeposition from the liquids in contact therewith. Accordingly, the natureand concentrations of ions in the water in contact with the clay candetermine the cations occupying the base-exchange sites. In most oilWell formations, the natural waters associated therewith contain sodiumas the predominant cation, with calcium, magnesium and other cationspresent in much smaller quantities. Since the base-exchange positions onthe clay are occupied by cations, in many cases the cation will besodium when natural ground waters such as those described above areassociated therewith. Unfortunately, however, as for example in the caseof the sodium form of montmorillonite, these clay minerals swell in thepresence of water or certain brines and can, in some instances, exertpressures up to thousands of pounds per square inch. Thus, dependentupon the amount of water absorbed, the clay can change to a rigid pasteor a gelatinous mass, or if sufficient water is present, the clay candisperse completely into the aqueous phase.

We have found that the difficulties noted above can be substantiallyreduced and a clay body can be stabilized to impart or maintainsatisfactory permeability to fiuids, improved mechanical strength andincreased resistance to chemical attack by treating such clay body withsubstituted ammonium ions derived from N-alkyl substitutedcyclohexylaminesfin which the N substituents have fewer than 4. carbonatoms, the total number of carbon atoms in the N-substituents. being atleast 3. While the substituted ammonium ions defined above are effectiveclay-stabilizing agents, the parent basic nitrogen compounds from whichthe substituted ammonium ions are derived have essentially noclay-stabilizing action.

The substituted ammonium ions can be obtained, among other ways, fromsalts prepared by reacting an appropriate basicnitrogen compound, of theclass describedwith an acid, preferably one whose anionic component willnot form a precipitate with ions associated with substances such asaqueous fluids with whichthe substituted ammonium salt may come incontact. Thus, ifthe fluids contain a sign ficant concentrationofalkaline earth ions, it is inadvisable to employ salts whose anioniccomponent may be Sulfate, oxalate, etc.,, since a precipitate canresult. Among the compounds which can be employed in preparing the saltsare hydrochloric acid, by drobromic acid, nitric acid, lactic acid,citric acid, salicylic acid, etc., lower fatty acids such as formic,acetic, propionic, etc., and methyl bromide, ethyl bromide, isopropyliodide, etc. Among the salts which are satisfactory for use inaccordance with the present invention are N,N-diethylcyclohexylammoniumchloride, N,N-diethylcyclohexylammonium bromide,N,N-diethylcyclohexylammonium iodide, N,N-diethylcyclohexylammoniumnitrate, N,N-diethylcyclohexylammonium formate,N,N-diethylcyclohexylammonium salicylate, N,Ndiethylcyclohexylammoniumlactate, N,2-trimethylenecyclohexylammonium chloride,N,2-trimethylenecyclohexylammonium iodide,N,2-trimethylenecyclohexylammonium propionate,N,2-trimethylenecyclohexylammonium acetatc,N,2-trimethylenecyclohexylammonium nitrate, N,2-trimethylenecyclohexylammonium formate, N,2trimethylenecyclohexylammonium salicylate,N,2-trimethylcnecyclohexylammonium citrate.

In treating the clay, substituted ammonium ions or mixtures of thesubstituted ammonium ions dissolved in any suitable polar solvent suchas water, methyl alcohol, ethyl alcohol, mixed solvents, etc. can beemployed. The solution employed can be'of any desired concentration,from as little as one-hundredth molar to a saturated solution, butpreferably in a concentration of about 0.75 to about one and one-halfmolar.

The amount of solution necessary to treat the clay body and obtain thebeneficial results of this invention depends on a number of variables,for example the amount of clay, the concentration of the treating,solution, the porosity of the clay body, the desired depth ofpenetration into the clay body and the type of clay to be treated. Ingeneral, the clay is contacted with solutions of substituted ammoniumions in such amounts as to provide. at least 1, and preferably at least5, milliequivalents of substituted ammonium ions per milliequivalent ofbase-exchange capacity of the clay. In any case, best results areobtained by using, an excess of substituted ammonium ions, measured asmilliequivalents, over the number of base-exchange positions, alsomeasured as milliequivalents, on the clay to be treated.

To treat the clay with the solution containing the substituted ammoniumions any suitable method that will. assure effective contact betweenthe. solution and the clay can be employed. In treating a formationadjacent a well, for example, the solution containing the substitutedammonium ions can be spotted adjacent the'formation'or formations to betreated and then be permitted to permeate the formation, pressure beingused to force the solution into the formation if desired. In addition,the solution can be used. to treat an oil well formation by spotting,prior to shooting, a sufficient amount of the solution in a well boreadjacent a section to be shot and then shooting. Also, in gunperforating or jet perforating a well, the solution can be spottedthrough the interval to be. perforated and the gun then inserted andfired in the hole opposite the. interval. In secondary recovery, such asa water flood program, the treating solutioncan be used in front of theflood to. stabilize the clay in the, formation as the flood. progressesthrough the formation, thus preeluding a drop in injection rate causedby reduced. per-- meability due to swelling and/or dispersing of theclay. In treating the formation adjacent a borehole of a well which isproducing hydrocarbons, the beneficial results of this invention can beobtained by treating the formation with sufiicient of the-treating fluidto obtain a penetration of at least one foot and preferably betweenabout 5' and 50 feet, and then returning, the well to production.

The. mechanism involved in treating clays in accord ance with ourinvention is, an ion-exchange reaction betweenexchangeable cations ofthe clay-and'thesubstituted ammonium ions inthe treating solution. Whenthe clay is contacted with the substituted" ammonium ions identifiedabove, the substituted ammonium ions exchangequickly and in anessentially irreversible manner withthe cations occupying thebase-exchange sites on the clay structure. As a result of thistreatment, hydrated,'swollen clay will shrink essentially irreversibly,unhydrated clay will be rendered insensitive to water and otherswellingagents, and the resistance of the clay to mechanical andchemical attack will be increased.

In order to demonstrate the efiectiveness of the substituted ammoniumions identified above as clay-stabilizing agents, wehave run a series oftests in which various substituted ammonium ions were employed. Thesubstituted ammonium ions were formed by dissolving in water saltsobtained by the reaction of the suitable basic nitrogen compound withhydrochloric acid. Montmorillonite was chosen as the clay for thesetests because of its very high ability to swell and disperse. The testscomprised placing 0.077 gram of montmorillonite (0.077 milliequivalentbase-exchange capacity) suspended in 5.0 milliliters of a salt solutionin a test tube. One liter of the salt solution prior to suspendingmontmorillonite therein contained 2,317 milligrams of sodiumbicarbonate, 279.9 milligrams of calcium chloride hydrate, 434.2milligrams of magnesium chloride hydrate, and 0.86 milligram ofmagnesium sulfate. The contents of the test tube were allowed to set for48 hours, after which the amount of precipitate was measured. Thesubstituted ammonium ion was then added to the contents of the test tubein an amount equal to five times the base-exchange capacity of the clayand the mixture was shaken for 15 minutes and subsequently allowed tostand for 24 hours. At the end of this period the volume of clayprecipitate was estimated and such quantity of supernatant liquid waswithdrawn from the test tube that the volume of the liquid and clayremaining was the same as the volume of the clay suspension originallytreated. Fifteen milliliters of distilled water were added to theresulting mixture and the test tube was shaken for 15 minutes andallowed to stand for 24 hours, after which the volume of clayprecipitate was again estimated. This cycle was repeated a number oftimes. At about the 15th test cycle and for one cycle only, a saltsolution similar to that in which the montmorillonite was initiallydispersed was substituted for the distilled water. Otherwise, theprocedure was not changed. Each cycle results in a decrease in the saltconcentration of the aqueous solution and the concentration of treatingagent in equilibrium with the clay precipitate. This dilution processwill cause swelling and/or dspersion of the clay if it has not beenefiectively stabilized. The substitution of the originalsalt solutionfor the distilled water at about the 15th test cycle is a test for thereversibility of the base-exchange reaction. Thus, if the treating agentis not held essentially irreversibly by the clay, part or all of it willbe exchanged for sodium ions or other cations from the salt solution andthe clay will swell and disperse in subsequent cycles of distilled waterleaching.

. The results of these tests are tabulated below in Table I.

Table I Compound Cycles to Cycles to Colloidal Swelling Appearand/r anceDispersion G yclohexylamrnonium chloride 7 18 N-methylcyclohexylammonium chloride 20 a Dicyclohexylammonium chloride 2N ,N-diethylcyclohexylammonium chloride.... N,2gzrimethylenecyclohexylammonium chlodenotes that the test wasdiscontinued at the end of 24 cycles and no swelling, disper ion, orcolloidal appearance was noted.

(a) denotes that the test had a colloidal appearance at the cycleindicated incolumn A" but had not swelled or dispersed at the end of 24cyc es.

. In above table, by colloidal'appearance it is meant that afterstanding 24 hours the supernatant liquid retains a turbid or opalescentappearance characteristic of that caused by the scattering of incidentlight by suspended colloidal particles. a colloidal condition indicatesthat the clay has 'not been stabilized by the substituted ammonium iontested. By swelling it is meant that the settled volume of the clay atthe end of 24 hours is at least 1 /2 times the settled volume of theclay at the beginning of the test. By dispersion it is meant that theclay is dispersed uniformly throughout the liquid so that at the end of24 hours no precipitate or sediment can be detected. Obviously, when theclay swells or disperses it has not been stabilized by the particularsubstituted ammonium ion tested.

The above table graphically illustrates the advantages of the presentinvention. Thus it can be seen that not all substituted ammonium ionsderived from cyclohexylamines, e. g., cyclohexylammonium chloride,N-methyl cyclohexylammonium chloride and dicyclohexylammonium chloride,are satisfactory as treating agents for stabilizing clays, for claystreated therewith were easily dispersed and resulted in aqueoussolutions having a colloidal appearance. Substituted ammonium ionsderived from N-alkyl substituted cyclohexylamines in which theN-substituents have fewer than 4 carbon atoms, the total number ofcarbon atoms in the N-substituents being at least 3, e. g.,N,N-diethylcyclohexylammonium chloride andN,2-trimethylenecyclohexylammonium chloride, proved to be veryeffective, for even at the end of 24 cycles the clay treated therewithwas unaffected by water or the salt solution.

- There follow illustrative embodiments of the actual practice of theprocess of this invention as applied to oil wells producing fromformations containing clay. It is understood that the proceduresdescribed are illustrative and the invention is not to be limitedthereby.

In treating a formation adjacent the bottom of a borehole to stabilizethe clay, said formation containing about 5 per cent by weight ofmontmorillonite and having a porosity of about 15 per cent, so as toattain a radial depth of treatment of at least 5 feet from the borehole,about gallons of a one-molar aqueous solution of substituted ammoniumions derived from N,N-diethylcyclohexylammonium chloride for each footof vertical thickness of the formation to be treated is used. Whiletheoretically only about 70 gallons of the above treating solution wouldbe needed to react with all of the clay in the above volume offormation, an excess over the theoretical quantity is employed to assurerapid and complete reaction with the clay. The treating solution isintroduced through a string of small diameter pipe lowered to within afew feet of the bottom of the hole and allowed to flow in by gravity.Since the treating solution has a much higher specific gravity thanwater, oil or ordinary oil field brines, it will displace water or oilopposite the formation to be treated and will then flow into theformation. As an aid in displacing the treating solution into theformation, pressure can be employed. The treating solution is introducedinto the formation slowly and allowed to remain in contact with theformation for about 24 hours, after which the unused portion, along withproduced fluid, is withdrawn from the well. It will be understood that,instead of treating formations adjacent the bottom of a borehole, anyselected formation interval above the bottom of the borehole can betreated in accordance with the invention by setting a bridge plug, inknown manner, at the bottom of the formation to be treated, andthereafter proceeding as described above considering the top of thebridge plug to be the bottom of the borehole.

The process of this invention is also used to advantage in secondaryrecovery operations wherein a displacement fluid such as water isapplied under pressure to an oil-bearing formation by means of speciallyequipped The appearance of such arous s input. wells. pene a in ai mat h7 Purp se offorcingtheoilout oflthe oil-bearing formation through anoutput well. penetrating saidformation. Such opera; tions are oftendeveloped in what is termed a five-spot patternwith theproducing welllocatedin the center of a square formed by water input wells at the fourcorners. By introducing any of the treating solutions disclosed hereininto the water input wells prior to injection of water, the treatingsolution will-move ahead of the ad vancing water and thus stabilize theclay in the formation before the clay has had. an Opportunity to come incontact with the injection water and. be deleteriously affected bycontact therewith. Inactualpractice, the treating solution is placedadjacent the formation to be treated by introducing the same through astring of small diameter pipe lowered to a point. adjacent the sectionof the formation to be treated in the manner described in the.paragraph. next preceding and is followed by normal injection of water.To establish a front of the treating solution about five feet thick(radially) ahead of the injection Water at a radius of about 20 feetfrom the borehole in a formation having the same montmorillonite contentand porosity described above, about 650 gallons of a one-molar aqueoussolution of N,Ndiethylcyclohexylammonium chloride is sulficient for eachfoot .of thickness (vertical) of the formation to be treated. Because ofprior treatment in accordance with the invention, a satisfactorypermeability of the clay during the water flood is maintained orimproved, thereby leading to more efiicient recovery of the fluids to beproducedl The treating solutions herein disclosed are also employed withadvantage in oll-well perforating. When clay-Water drilling muds areused in rotary drilling, they seal oi the openings in porous formationsencountered while drilling. v tions are cased off and the casingmust beperforated for production, the sealing property of clay-water muds canbe detrimental. Since the hydrostatic head of the mud in the boreholeexceeds the formation pressure, when the casing is perforated theclay-water mud rushes into the perforated formation until a mud cakeseal is es-. tablished or the pressure is balanced. This often isaccompanied by a fresh water loss to the formation, which in the clayformations described, swells the clay which is present. In addition,there often results blocking of the perforated formation to such anextent that on sub.- sequent completion of the well the perforationshave to be washed or acidized with reagents known as mud clean outagents.

To avoid such difiiculties in perforating operations in accordance withthe present invention, a string of tubing is lowered into the boreholeso that its lower end is rad jacent the bottom of the section to betreated and about 300 gallons of asui-table oil-base drilling fluid. isintroduced through the tubing to displace the clay-water drill.- ing mudupwardly in the borehole. About 150 gallons of a one-molar aqueoussolution of the treating solution, e. g., N,N-diethylcyclohexylammoniumchloride, for each foot of thickness of the formation is thereafterintroduced through the tubing and in turn displaces the oil-basedrilling fluid upwardly in. the borehole. The perforating gun, eitherbullet or jet, is then lowered into the treating solution opposite theformation to be treated and the casing perforatedin the usual manner.The hydrostatic head in the borehole exceeds the formation pressure andthus will force the treating solution into the formation. In this way,the naturally-occurring clay, which was exposed to fresh water lost tothe formation from the clay-water drilling fluid, will be shrunken andstabilized and when the wall is permitted to flow, or is swabbed orpumped, the unused clay-stabilizing agent the treating solution will beproduced from the formation. This operation will leave the formationsubstantially free from plugging by mud cake or other hydrated clay.Thus, by employing any one of. the treating agents In well completionswhere such formadisclosed herein while perforating, the formation willbe pre vented from being mudded off, the harmful effects of, fresh wateron naturally-occurring claywill be nulli fied, themecessity, for washingperforations with so-ca'lled mud acids will be eliminated, and the useofconventional clay-water drilling muds will be permitted in areas wherethe producing formations contain swelling-type clays and the moreexpensive oil-base muds are commonly used.

Similarly in oil, Well shooting in open hole with high.

explosives, such as nitroglycerine, trinitrotoluene, etc, the freshlyexposed formatti-on may also be contacted with a clay-water drillingfluid with the accompanying harm]- ful eifects described above. Thedrilling fluid opposite the formation to be treated in such case can bereplaced with. an oil-base drilling fluid followed by the treatingsolution in the manner described above, and the explosive can be loweredinto the solution and detonated in the customary manner. The beneficialresults. obtained in employing the treating solutions of the inventionwhile perforating will also accompany their use with high er;- plosives.I

While We have found that the specific substituted ammonium ionsdisclosed herein or mixtures thereof are satisfactory for the purposesof this invention, there are certain instances wherein it isadvantageous to employ in admixture therewith other substituted ammoniumions not specifically disclosed herein but which have similar propertiesthereto, as for example, the substituted am; monium ions disclosed inour copending applications filed concurrently herewith, applicationSerial Nos. 469,855 to,469, 8 6 0, inclusive, as well as in the otherconcurrently filed .copending applications in the name of William E.Brown, application Serial Nos. 469,854 and 469,862. For example,although by far the greatest portion of the base-exchange sites on aclay mineral surface will have an area approximating the average areaper exchange site, a small number of sites will have an areaconsiderably less than the average. Because of the spatial configurationof their hydrophobic part, certain substituted ammonium ions will not beable to occupy these smaller sites, in which case it is advantageous touse one or more additional substituted ammonium ions of diiferentspatialconfiguration which can occupy the remaining posit-ions and. thuscomplete the stabilization reaction. It is believed that this; use isespecially advantageous in the case of the mixed-layer clay minerals.

@bviously, many modifications and variations of the invention, ashereinabove set forth, may be made without departing from the spirit andscope thereof, and therefore only such limitations should be imposed asare indi-catedin the appended claims.

We claim:

11. A method, of stabilizing a clay-containing body which comprisescontacting such clay-containing body with substituted ammonium ionsderived from N-alkyl substituted cyclohexylamines in which theN-substituents have fewer than 4 carbon atoms, the total number ofcarbon atoms in the N-substituents being at least 3.

2 A method of stabilizing a clay-containing body as in claim 1 in whichthe clay-containing body comprises at least one clay mineral selectedfrom the class consisting of the niontmorillonite group, hydrousmicagroup, chlorite group, and kaolin group.

3. A method of stabilizing a clay-containing body which comprisescontacting such clay-containing body with substituted ammonium ionsderived from N,N-diethylcyclohexylamine. i

4. A method of stabilizing a clay-containing body which comprisescontacting such clay-containing body with substituted ammonium ionsderived from N,2-trimethylenecyclohexylamine.

5. A method of stabilizing a clay-containing formation adjacent a wellbore which comprises contacting such sl ntainin t met sn with titutedamm i ions derived from N-alkyl substituted cyclohexylamines in whichthe N-substituents have fewer than 4 carbon atoms, the total number ofcarbon atoms in the N-substituents being at least 3.

6. A method of stabilizing a clay-containing formation adjacent a wellbore which comprises contacting such clay-containing formation withsubstituted ammonium ions derived from N,N-diethylcyclohexylamine.

7. A method of stabilizing a clay-containing formation adjacent a wellbore which comprises contacting such clay-containing formation withsubstituted ammonium ions derived from N,2-trimethylenecyclohexylamine.

8. A method of recovering oil from an oil-bearing formation containingclay, wherein a displacement fluid under pressure is applied to saidformation through at least one input well penetrating said formation,and wherein oil is recovered from an output well penetrating saidformation, which comprises introducing a treating solution containingsubstituted ammonium ions derived from N-alkyl substitutedcyclohexylamines in which the N-substituents have fewer than 4 carbonatoms, the total number of carbon atoms in the N-substituents being atleast 3, into said input well, thereatfer introducing said displacementfluid under pressure into said input well, forcing said treatingsolution through said formation by means of said displacement fluid, andrecovering oil from said output well.

9. A method of recovering oil from an oil-bearing formation containingclay, wherein a displacement fluid under pressure is applied to saidformation through at least one input well penetrating said formation,and wherein oil is recovered from an output well penetrating saidformation, which comprises introducing a treating solution containingsubstituted ammonium ions derived from N,N-diethylcyclohexylamine intosaid input well,

10 thereafter introducing said displacement fluid under pres sure intosaid input well, forcing said treating solution through said formationby means of said displacement fluid, and recovering oil from said outputwell.

10. A method of recovering oil from an oil-bearing formation containingclay, wherein a displacement fluid under pressure is applied to saidformation through at least one input well penetrating said formation,and wherein oil is recovered from an output well penetrating saidformation, which comprises introducing a treating solution containingsubstituted ammonium ions derived from N,2-trimethylenecyclohexylamineinto said'input well, thereafter introducing said displacement fluidunder pressure into said input well, forcing said treating solutionthrough said formation by means of said displacement fluid, andrecovering oil from said output well.

References Cited in the file of this patent UNITED STATES PATENTS2,262,428 Leitz Nov. 11, 1941 2,320,009 Ralston et al. May 25, 19432,348,458 Endersby May 9, 1944 2,414,668 Ratcliife Ian. 21, 19472,419,755 Albaugh Apr. 29, 1947 2,472,400 Bond June 7, 1949 2,531,440Jordan Nov. 28, 1950 2,599,342 Meadors June 3, 1952 2,603,598 MeadorsJuly 15, 1952 2,607,744 Viles Aug. 19, 1952 2,659,693 Lytle Nov. 17,1953 2,681,314 Skinner June 14, 1954 FOREIGN PATENTS 881,982 GermanyJuly 9, 1953

1. A METHOD OF STABILIZING A CLAY-CONTAINING BODY WHICH COMPRISESCONTACTING SUCH CLAY-CONTAINING BODY WITH SUBSTITUTED AMMONIUM IONSDERIVED FROM N-ALKYL SUBSTITUTED CYCLOHEXYLAMINES IN WHICH THEN-SUBSTITUENTS HAVE FEWER THAN 4 CARBON ATOMS, THE TOTAL NUMBER OFCARBON ATOMS IN THE N-SUBSTITUENTS BEING AT LEAST 3.